1. Field of the Invention
The present invention relates to an analog-to-digital converting circuit and, more particularly, to a technology of cyclic AD converters.
2. Description of the Related Art
In recent years various additional functions such as an image shooting function, an image reconstruction function, a moving image shooting function, a moving image reconstruction function are provided in a portable phone set. As a result of this, there is a growing demand for miniaturization of and power-saving in analog-to-digital converting circuits (hereinafter referred to as “AD converters”). A cyclic AD converter is known as one configuration of AD converters. For example, reference is made to Japanese Laid-Open Patent Application No. 11-145830.
The cyclic AD converter mentioned above is more advantageous than a multi-stage pipeline AD converter in that the circuit area is reduced since the number of components constituting the cyclic AD converter is smaller than that of the multi-stage AD converter. However, reduction in circuit area is normally a trade off for a reduced conversion speed. Therefore, a task to be challenged in a cyclic AD converter is to promote efficiency in configuration and power consumption.